Hello,

You can do this but you will have to add custom css for each portfolio item you want full-width. Please add this code into your custom css box:

.postid-4051 .portfolio_single.single_portfolio_container .portfolio_single h4 {
    display: none;
}
.postid-4051 .portfolio_single.single_portfolio_container .row-fluid .span3 {
    display: none;
}
.postid-4051 .portfolio_single.single_portfolio_container .row-fluid .span9 {
    width: 100%;
}

Result screenshot.
Change the post id for each item you will edit. You can find the id using instapect element (press F12 in your keyboard, like shown in the screenshot).

Let us know.

Best regards!

Hello,

Yes, you have to add the custom css block for each post you want to change. The only thing you will change in it, is the post id. Because each post is identified by an unique id.
Example:
Post: https://www.maralombardi.it/archives/mara-lombardi-portfolio/urban-art-synesthetic-dark-room
Code:

.postid-2794 .portfolio_single.single_portfolio_container .portfolio_single h4 {
    display: none;
}
.postid-2794 .portfolio_single.single_portfolio_container .row-fluid .span3 {
    display: none;
}
.postid-2794 .portfolio_single.single_portfolio_container .row-fluid .span9 {
    width: 100%;
}

screenshot

Post: https://www.maralombardi.it/archives/mara-lombardi-portfolio/great-vitj-lake-2
Code:

.postid-4047 .portfolio_single.single_portfolio_container .portfolio_single h4 {
    display: none;
}
.postid-4047 .portfolio_single.single_portfolio_container .row-fluid .span3 {
    display: none;
}
.postid-4047 .portfolio_single.single_portfolio_container .row-fluid .span9 {
    width: 100%;
}

screenshot
..and so on.

Let us know if you need further help.

Best regards!